Odorizer for natural gas lines



Nov. 4, 1941 J. T. RUTHERFORD ETAL ODORIZER FOR NATURAL GAS LINES FiledFeb. 15, 1940 A it 34- H 35 26 28 35 1 lo INVENTORS JOHN T. RUTHERFORDWILLIAM ESTOCKJn F1952.

, z BY ATTORNEY Patented Nov. 4, 1941 .ononlzan FOR. NATURAL GAS LINESJohn '1. Rutherford, Berkeley, and William E. Stock, Jr., Richmond,Calif.,- assignors to Standard Oil Company of California, San Francisco,Calif., a corporation of Delaware Application February 13, 1940, Serial.No. 318,724

6Claims.

This invention relates to devices for introducing a volatile liquidhaving a distinctive odor into a stream of natural gas flowing in aline,

and particularly refers to one of the by-pass type which utilizes acombination of surface evaporation and atomization to securesubstantially constant and complete saturation of that portion of thegas passing through the device, at widely varying gas flow rates.

Generally, aby-pass type odorizer is one in which a proportional part ofthe gas passing through a flow restriction, such as a valve or orificeplate in a main line, is diverted or by-passed through pressureconnections, suitably spaced from the flow restriction, into and througha chamber in which a volatile liquid is exposed to be evaporated. Thepressure differential set up by the flow restriction constitutes thedriving force to by-pass the gas into the chamber and to return it againto the main gas stream. Desirably the by-passed gas is substantiallycompletely saturated with the volatile liquid, and the degree ofodorization of the total gas flow, usually expressed in gallons permillion cubic feet, is controlled by the size of the orifice or thedegree of opening of the valve which comprises the flow restriction inthe main line.

The flow rate in many natural gas lines varies through very wide ranges,and this is particularly true in those numerous scattered installationsof small throughput to which the present invention is particularlyadapted. Accordingly, two types of evaporation promoting and controllingmeans are employed in combination, one adapted to saturate the by-passedgas at very low flow rates, and the other adapted to cooperate with andsupplement the first when the gas flow increases, this action beingentirely automatic and not employing external forces or moving partsother than the gas and liquid which are being handled.

Heretofore most by-pass odorizers utilized deflected gas streams whichincreased turbulence to enhance vaporization of the odorant liquid.Other types have used wicks of capillary material to increase wettedsurface area. In those designs the degree of saturation of the gas withodorant liquid was largely a function of the flow rate, at low rates agreater degree of saturation being obtainedbut decreasing rapidly withincreasing flow rates. Thus the saturation, and hence odorantevaporation, would vary with gas flow rate. In certain designs an at mptwas made to obtain saturation at all tim by submerging the gas inlet andforcing the gas to bubble through a depth of liquid. Such an arberdirecting the incoming gas through a prerangement obviously could notprovide odoriza tion at main line gas flow rates below those which 7would create a. pressure differential equal to the static head of theliquid, and true proportioning could not be obtained at higher flowrates because of the added static pressure on the bypassed gas, whichadded a constant value to the proportional pressure differential causedby the flow restriction in-the gas line.

This invention comprehends broadly a chamber for odorant liquid, a gasinlet for the chamdetermined path above the liquid level and in contactwith a wetted wick or extended capillary surface, and means cooperatingwith the gas inlet and only efi'ective at higher gas flow rates toatomize the odorant liquid into the by-passed gas stream, thereby givingsubstantially complete saturation of the latter under flow conditionsthat are of such magnitude that the evaporative capacity of wick orextended capillary surface would be inadequate. In order to insure thatthe composition'of the odorant liquid remains substantially constantover long periods of. use

so that evaporation from an equilibrium mixture is obtained, it isdesirable to regulate the liquid level range within limits and also toprovide either an appreciable volume of odorant liquid in theevaporating chamber, so that additions of fresh, unweathered liquid willnot unduly affect its vapor pressure and volatility, or to provide aseparate odorant storage reservoir and a liquid level control means thatwill continuously replenish the odorant in the evaporating chamber as itis volatilized into the gas.

It is an object of this invention to provide a simple and automaticallyacting evaporative type gas odorizer that will give substantiallycomplete saturation of gas by-passed from a main line for widervariations of flow in the latter than has heretofore been possible.

Another object is to provide a by-pass type odorizer that will give moretruly proportional feed of odorant Withrespect to gas volume than inthose heretofore known.

Another object is to provide an odorizer in which there are no movingparts and small ports or passages to clog, and which is so economical tofabricate, install and maintain that its use may be'extended tolocations where odorization has not been feasible. I

These and other objects and advantages. will be further apparent fromthe following description and from the attached drawing, which forms apart of this specification and illustrates a preferred embodiment of theinvention as well .as an alternative form which has been found to bedesirable.

In the drawing, Figure 1 is a vertical sectional view of an odorizerconnected to a typical gas line and illustrates a preferred form ofevaporating and atomizing means for the odorant liquid.

Figure 2 is a vertical sectional view of an alternative form of odorizerembodying this invengas outlet 36 from chamber 14 may also extendthrough closure plate I! at a point above the liquid level of theodorant l9, and communicates with the gas main I through the reducedpressure connection l3. At low gasfiow rates in main l0, which would notcause a high enough tion and arranged to maintain a constant liquidlevel in the evaporating chamber.

Figure 3 is a vertical sectional view of one form of gas inlet andodorant atomizer for the apparatus of Figures 1, and 2.

Referring to the drawing and particularly to Figure 1, reference numeralI0 designates a pipe line through which natural gas is flowing in thedirection indicated by the arrow. A flow restriction means, which may bea valve or, in this case, an orifice plate I I, is placed in line Hi to.create a pressure differential therein in the I, well knownmanner.---Valved pressure connec- ,tions l2 and I3 constitute,respectively, the high pressure and reduced pressure connections to theevaporating chamber and odorant reservoir l4. Preferably the chamber I4is buried in the earth I5, insulated, or otherwise arranged to be at aAlso,

horizontally so that changes in odorant quantity therein will modify theliquid level as little as possible. This is particularly true in theembodiment of Figure l, where the liquid level falls as the odorant isevaporated from chamber [4.

In this example, chamber ll comprises a cye lindrical shell l6 closed atone end and provided with a removable closure such as a bolted plate i!at the other end. A straight pipe I8 extends to the surface of the earthfor gauging the level of the odorant I 9 in the chamber and forreplenishing the same, and is normally closed by a valve 20. A suitablevalved drain 2i is provided to empty chamber H when required.

The high pressure connection l2 from pipe It forms the gas inlet tochamber H, extending into the chamber a short distance from the innerface of plate ll, above the liquid level of odorant I9 and terminatingina Venturi type aspirating nozzle generally designated 22. One formsuitable for nozzle 22 is shown in Figure 3, and, in that example,consists of a body 23 threaded onto pipe connection l2, said body havinga constricted throat or bore 24, with a side passage 25 terminatingtherein. A conduit 26 leads downwardly from passage 25 to a point belowV odorant.

Extending into chamber'll from the inside face of plate I! andsurrounding the gas inlet nozzle 22 is an absorbent extended capillarysurface, in this case a helically wound or woven "cotton wick 28,desirably supported by fluidpermeable means such as a perforated metaltube 29, and with its lower portion below the level pressure drop acrossrestriction II to actuate the nozzle 22 to inspirate and atomize theodorant,

the by-passed gas passing outwardly from nozzle 22 and flowing over thewetted surfaces of wick 28 will be found to evaporate sufficient odorantto be substantially completely saturated. Thus a fully automatic meanshave been provided to by-pass gas from a main at a rate proportional tothe flow of gas therein, the by-passed gas moving into and through anodorant evaporating chamber where it is substantially saturated bysimple evaporation at low gas flow rates and by a combination of suchevaporation and liquid atomization at high gas flow rates, the gas thenbeing returned to the main where it imparts a distinctive odor at acontrolled and predetermined rate to the main gas stream. At the highgas flow rates, the mist or fog from the nozzle 22 will also wet thecapillary material 28 above the liquid level, thereby insuring that nopart of it will be dried out and rendered ineffective.

The arrangement of Figure'2 is similar in most respects to that justdescribed, the principal difference being that the odorant liquid IS inchamber I4 is maintained at a substantially constant level A and, as itis evaporated, is replenished from a storage reservoir 30 through astrainer 3| and a liquid level controller 32, the vapor space of thelatter being connected in the usual manner to the vapor space of thereservoir 30 by a pressure equalizing line 33. In that example theperforated tube support 29 for wick 2B is preferably arranged to besubstantially concentric with the small diameter shell 34 and spacedtherein by lugs 35. In the arrangement of Figure 1, the liquid levelpreferably should be maintained in the range B, which should representnot over about 25% of the total liquid volume of odorant charge,particularly where the latter is a mixture of components havingdifferent degrees of volatility, so that approximate equilibriumvaporization will be obtained.

An example of an apparatus constructed according to this disclosuremaintained substantially complete saturation in the by-passed gas atflow rates through the device ranging from about 510 to 450 cubic feetper hour, the pressure differential to cause such flow ranging from 1 to130 inches of water. At differentials below about 2 inches of water theVenturi nozzle did not atomize and purely evaporative operation resultedwithout affecting the proportioning of the liquid odorant to the naturalgas.

Although specific constructions-have been described and illustrated,itis to be understood that many changes and modifications can be madewithout departing from the invention, and all such alterations that fallwithin the scope of the appended claims are embraced thereby.

We claim:

1. A by-pass type odorizer for natural gas lines, comprising a chamberfor odorant liquid, means in said chamber forming an extended capillarysurface to be wetted by said odorant. a gas inlet of odorant I! so as tobe wetted thereby. The

for said chamber above the level of liquid therein and adjacent saidcapillary means to direct gas thereover and to evaporate said odorantliquid therefrom, a gas outlet above the liquid level in said chamber,and an aspirating nozzle for said gas inlet to atomizeodorant liquidinto said gas and onto said extended capillary surface above the liquidlevel to wet the same with odorant liquid at high flow rates throughsaid chamber.

2. An odorizer according to claim 1, in which the means forming saidextended capillary sur-' face comprises a generally hollow cylinder ofabsorbent material surrounding said gas inlet and defining the passageor gas through said chamber.

p 3. An odorizer according to claim -1, in which the means forming-saidextended capillary Slitface comprises a generally hollow cylinder ofabsorbent material surrounding said gas inlet, and

means for supporting said cylinder in contact with said liquidsubstantially throughout its length.

4. An odorizer according to claim- 1, with the addition of means formaintaining a predetermined liquid level range in said chamber.

5. An odorizer according to claim I, in which said chamber comprises ahorizontal cylinder closed at both ends and the means forming saidextended capillary surface comprises a hollow cylinder extendingparallel to and substantially throughout the length of said chamber.

6. A by-pass type odorizer for natural gas lines said last-named meansto be wetted by odorant liquid in said chamber, a portion or saidabsorbent material extending above the level oiliquid in said chamber, agas outlet for said chamber above the liquid level therein, and meanscontrolled by th passage of gas through said inlet for atomizing odorantliquid into said gas stream and onto said absorbent material above theliquid level to wet the same with odorant material at high gas flowrates.

JOHN T. RUTHERFORD.

WIILIAM E. STOCK, JR.

